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                            <div style="color:gray; word-break: break-all; font-size:12px;">原英文版地址: <a href="https://www.elastic.co/guide/en/elasticsearch/reference/7.7/index-rollover.html" rel="nofollow" target="_blank">https://www.elastic.co/guide/en/elasticsearch/reference/7.7/index-rollover.html</a>, 原文档版权归 www.elastic.co 所有<br/>本地英文版地址: <a href="../en/index-rollover.html" rel="nofollow" target="_blank">../en/index-rollover.html</a></div>
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<strong>重要</strong>: 此版本不会发布额外的bug修复或文档更新。最新信息请参考 <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/index.html" rel="nofollow">当前版本文档</a>。
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<span class="breadcrumb-node">Rollover</span>
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<h2 class="title">
<a id="index-rollover"></a>Rollover<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/ilm/index-rollover.asciidoc">edit</a>
</h2>
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<p>When indexing time-series data like logs or metrics, you can’t write to a single index indefinitely.
To meet your indexing and search performance requirements and manage resource usage,
you write to an index until some threshold is met and
then create a new index and start writing to it instead.
Using rolling indices enables you to:</p>
<div class="ulist itemizedlist">
<ul class="itemizedlist">
<li class="listitem">
Optimize the active index for high ingest rates on high-performance <em>hot</em> nodes.
</li>
<li class="listitem">
Optimize for search performance on <em>warm</em> nodes.
</li>
<li class="listitem">
Shift older, less frequently accessed data to less expensive <em>cold</em> nodes,
</li>
<li class="listitem">
Delete data according to your retention policies by removing entire indices.
</li>
</ul>
</div>
<p>Rollover relies on three things:</p>
<div class="ulist itemizedlist">
<ul class="itemizedlist">
<li class="listitem">
An <em>index template</em> that specifies the settings for each new index in the series.
You optimize this configuration for ingestion, typically using as many shards as you have hot nodes.
</li>
<li class="listitem">
An <em>index alias</em> that references the entire set of indices.
</li>
<li class="listitem">
A single index designated as the <em>write index</em>.
This is the active index that handles all write requests.
On each rollover, the new index becomes the write index.
</li>
</ul>
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<h3 class="xpack">
<a id="ilm-automatic-rollover"></a>Automatic rollover<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/ilm/index-rollover.asciidoc">edit</a><a class="xpack_tag" href="https://www.elastic.co/subscriptions"></a>
</h3>
<p>ILM enables you to automatically roll over to a new index based
on the index size, document count, or age. When a rollover is triggered, a new
index is created, the write alias is updated to point to the new index, and all
subsequent updates are written to the new index.</p>
<div class="tip admon">
<div class="icon"></div>
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<p>Rolling over to a new index based on size, document count, or age is preferable
to time-based rollovers. Rolling over at an arbitrary time often results in
many small indices, which can have a negative impact on performance and
resource usage.</p>
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